Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the annotations by disclosing the full lifecycle: the file is downloaded from download_url, stored in Cloudflare R2 during the job, processed via a headless browser, and deleted when the job ends, plus result links that expire after 1 hour. These operational traits (ephemeral storage, expiry, processing pipeline) are exactly the context an agent needs.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose, input contract, output behavior, and lifecycle are front-loaded in that order, with no filler sentences. The infrastructure sentence (R2, headless browser, Cloudflare) is dense but carries real behavioral value rather than padding.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description correctly steps in to describe the return (download links with a 1-hour expiry) and input cleanup. It stops short of clarifying which formats actually support bitrateKbps, a minor gap for a 3-param tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100%, so the baseline is 3. The description earns extra credit by adding a caveat the schema lacks: outputFormat and bitrateKbps apply only 'where the tool supports them', flagging that valid values may be format-dependent and not universally accepted.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Extracts the audio track from a video file') with concrete input examples (MP4, MOV, MKV). It is distinguishable from the many audio-conversion siblings by its video input, though it never names a sibling to route against.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The 'Input: one file with a public HTTPS download_url' line implies the usage context, but there is no explicit when-to-use guidance or contrast against siblings like audio_converter or mp3_converter for already-audio inputs. Usage must be inferred.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.